1. Field of the Invention
The invention relates to an image recording device, in particular, an image recording device adopting a line print system and forming an image on a recording medium with the use of an ink including a light curable component.
2. Description of Related Art
In general, as an image recording means capable of printing on various types of recording mediums, an image forming means with a gravure printing system and one with a flexographic printing system are known. These image forming means, which are to feed ink into a reentrant portion formed on a printing surface and to directly transfer it onto a recording medium, have characteristics such as capability of colorfully expressing letters, marks and graphics, capability of printing fast onto large amount of recording medium and the like. These days in particular, printing is performed on various packaging medium, and in such a case, it is effective to use the image forming means with the gravure printing system or the flexographic printing system. However, at a pre-step of actually performing the printing, these image forming means need to go through a prepress step for making a plate, and it is necessary to spend cost and time for the prepress step. Given this factor, in the case of performing small-amount but many-variety printing, it is desirable to have means to perform the printing without a plate in accordance with either a transparent or opaque packaging medium.
In view of this, as means capable of printing on various types of recording mediums, an image recording device with an inkjet system has been conventionally known. The image recording device with an inkjet system is to record an image on a recording medium by discharging an ink to be dropped and fixed on the recording medium, the ink discharged from nozzles provided on a plane of a recording head opposed to the recording medium, and the image recording device with an inkjet system has an advantage of being capable of printing according to demand because the prepress step is not necessary. However, in the case of using the inkjet image recording device in general, an ink easily gets blurred on a recording medium, and therefore it is only possible to perform the image recording on a recording medium with high ink absorbability. In particular, it is significantly difficult to perform the image recording on transparent resin film or the like, which does not have a specific image-reception layer provided therein.
On the contrary, as means capable of forming an image even on a recording medium with little ink absorbability such as a medium made of resin film, plastic or the like, these days, an inkjet image recording device with the use of ultraviolet-ray curable ink is known (for example, see Japanese Patent Application Publications Nos. Tokukai 2001-310454, and Tokukai 2001-131452). These devices have a structure where, with the use of ultraviolet-ray curable ink which contains photoinitiator having predetermined sensitivity with ultraviolet rays, by irradiating ultraviolet rays to an ink dropped on a recording medium, the ink gets cured and fixed on the recording medium. With these devices, it is possible to easily perform the printing on either a transparent or semi-transparent (translucent) packaging medium.
In addition, if the printing to be performed on a transparent or semi-transparent packaging medium or the like, there are cases of performing the printing over a printing surface on which an image recording has been performed for the purpose of maintaining durability against scratch. This is called, “back printing”. Further, if the printing is to be performed on a transparent or semi-transparent packaging medium, there are cases of performing the printing in advance on the entire surface of the packaging medium and then performing the image recording with an ink of each color over the recording medium for making the recorded image by the ink of each color stand out visually. This is called “front printing”. For example, if it is necessary to print letters, marks, graphics or the like over a background color after a specific color such as white or the like is printed as the background against a transparent packaging medium, when the back printing is to be performed, an ink for a background such as white or the like may be printed, and when the front printing is to be performed, an ink for a background such as white or the like is printed firstly, and then an ink or each color may be printed. Further, in the case of performing the printing on a transparent or semi-transparent packaging medium or the like, as means with which it is possible to obtain substantially the same effect as the “front printing”, by which it is possible to make a recorded image by color inks of each color stand out, a duplex printing by which printing is performed with an ink for a background over the entire recording medium, and then printing is performed with an ink of each color on the opposite side of the recording medium is available.
In this aspect, as such an inkjet image recording device performing the printing on a transparent or semi-transparent packaging medium with the use of an ink for a background, an image recording device with a serial print system which performs image recording by moving a recording head in a main scanning direction back and forth, may be used.
However, in order to print the ink for a background such as white or the like as a background by the image recording device with the serial print system, it is necessary to additionally have a recording head of the ink for a background color on a carriage, the recording head being located apart from a recording head for a color purpose, and thereby it makes the carriage larger, which makes the entire image recording device larger correspondingly, and further it makes the device structure complicated. For example, in particular, in a case of mounting the recording head which discharges the ink for a background and the other recording head on the same carriage, weight of the carriage increases, and thereby it is difficult to maintain scanning speed and dropping accuracy which could be achieved in the case without having the recording head of the ink for a background.